In general, a door mirror for a vehicle such as a door mirror for an automobile can be folded to a vehicle-body side and retained in this state, for parking or the like. FIG. 5 is an explanatory view illustrating a general structure of the automobile door mirror. As illustrated in FIG. 5, a foldable unit 53 is incorporated into a mirror housing 52 of a door mirror 51. A mirror 54 and a mirror-tilting mechanism 55 are mounted to the foldable unit 53. The foldable unit 53 is mounted onto a stay 56 mounted to the vehicle-body side. A setting plate 58 including a rotation pivot 57 is mounted to the stay 56. The foldable unit 53 is turnably mounted to the rotation pivot 57 located on the setting plate 58.
A stopper 59 is provided to the foldable unit 53 so as to stop and retain the door mirror 51 in a predetermined turning position. Corresponding to the stopper 59, a stopper receiver 60 is provided on the stay 56 side. The abutment of the stopper 59 against the stopper receiver 60 regulates a turning operation of the foldable unit 53. In the case of the door mirror 51, when the foldable unit 53 is folded to be located in a storing position (fallen position) for parking or the like, the stopper 59 comes into abutment against the stopper receiver 60. When the foldable unit 53 is unfolded to be located in a set position for use (standing position) for running or the like, the stopper 59 is fitted into a concave portion (not shown) provided on the stay 56 side. The fitting of the stopper 59 into the concave portion retains the foldable unit 53 in the predetermined standing position.
The mirror housing 52 is positioned and fixed with the foldable unit 53 in a predetermined positional relationship. The mirror housing 52 turns together with the foldable unit 53. For example, in the case of the door mirror 51 illustrated in FIG. 5, the mirror housing 52 and the foldable unit 53 are threadably fixed at a screwing portion 61. FIG. 6 is an explanatory view illustrating a configuration of the screwing portion 61. As illustrated in FIG. 6, the screwing portion 61 includes a screw-fixing hole 62 on the foldable unit 53 side and a screw-insertion hole 63 on the mirror housing 52 side. For fixing the foldable unit 53 to the mirror housing 52, the screw-fixing hole 62 and the screw-insertion hole 63 are aligned with each other. Next, a setscrew 64 such as a tapping screw is screwed into the screw-insertion hole 63 so as to fix the mirror housing 52 and the foldable unit 53 to each other.    Patent Document 1: Japanese Patent Application Laid-open No. Hei 08-2324